Free_Astronomy_-_SeptemberOctober_2019

ASTRONAUTICS 41

T

oday, we have the technological

knowledge necessary to make long

journeys within the inner Solar Sys-

tem. We could return to the Moon or travel

to Mars simply by using what we have al-

ready designed. That said, there is a worry-

ing unknown that prevents us from doing

so airily, and we are not referring to the

availability of adequate funding that we

take for granted here. We refer instead to

our incomplete knowledge of the effects

that space radiation can have on the bod-

ies of astronauts engaged for weeks,

months or even years in interplanetary

space or on the lunar or Martian surfaces.

Although almost sixty years have passed

since the launch of the first man into orbit,

and in spite of significant research into the

possible pathologies attributable to space

radiation, our understanding of the risks

space entails for astronauts who remain

there for a long time is still very limited

and a matter of discussion. In particular,

there are significant disparities between

basic research results and observed empiri-

cal effects seen in astronauts exposed to

non-negligible periods of space radiation.

This is mainly due to various factors that

limit the simulations in terrestrial environ-

ments compared to the complex and rap-

idly changing space weather, as well as the

limited extrapolation of studies to human

beings based on models developed for an-

imals. For several reasons, these animal

models do not faithfully represent the ac-

tual human space radiation operating en-

vironment, and they even less (or not at all)

represent the complexity of human physi-

ology. Specifically, models developed for a

variety of animal species with different

sensitivities and radiation responses may

not be representative of human responses

to exposures of equal intensity. Moreover,

experimental models are based on histori-

cal epidemiological studies that include ex-

treme cases of radiation exposure, such as

S

pace radiation consists of not only photons,

but protons and many of the elements of

the periodic table. They enter the human body

at energies that can approach the speed of

light and can damage DNA. [NASA]

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